The No. 3-ranked Russian avenged her 6-3, 6-2 loss in the 2010 Wimbledon final, which turned out to be Williams' last match for almost a year. Williams won her fourth title at the All England Club, but stepped on broken glass at a restaurant in July and needed two foot surgeries. She later developed blood clots on her lungs.

Williams showed her trademark tenacity in the third set, coming back from 5-2 down to make it 5-5, saving three match points at 5-4. But Zvonareva immediately broke again and a tiring Williams couldn't muster another rally.

Williams lost on grass for the first time since she dropping the 2008 Wimbledon final to her sister Venus. On Wednesday, Serena was awarded a Wimbledon seeding of No. 7, which is 19 places above her ranking.

Despite the loss, Williams is pleased with her preparations for the defense of her title — and even happier that the foot injury is no longer troubling her.

"It was a good two matches for me," she said. "I couldn't be happier with the amount of tennis I played so it's good, just keep going.

"I haven't played in almost a year, so I'm a little sore. But it's good that I'm sore now because hopefully next week I won't be as sore. (The foot) is holding up really well, and I'm just really excited about that."

Venus Williams is returning from a five-month layoff because of a hip injury, and she reached the quarterfinals with a convincing 6-3, 6-2 win Wednesday over Ana Ivanovic.

Serena looked set to join her in the last eight when she served for the match at 5-4 in the second set against Zvonareva. But when facing a break point, Williams had a double-fault and Zvonareva rediscovered her confidence.

Leading 6-5 in the tiebreaker, the Russian drove a winning forehand into the corner, with Williams on her backside after slipping on the baseline.

Williams appeared tired in the third set. She came to the net behind her serve to finish the points quickly, and was often out of position. Facing an opponent with a reputation for throwing away a lead, she kept fighting.

Trailing 5-4, Williams hopped on one foot and looked surprised and relieved as a bold backhand winner looped onto the line to save a second match point.

Zvonareva then overhit a backhand to make it deuce, before she thought she caught the line with a half-volley. The ball was called out, though, and despite her complaints, Williams had a break point, which she took with a backhand winner.

But Williams was broken at 15 in the next game. Zvonareva moved into a 40-0 lead and then powered a forehand winner onto the baseline to claim victory on her fourth match point.

"It's never easy against Serena," Zvonareva said. "She's a great fighter and she came up with some great shots at the very important moments. I kept fighting and I'm really happy I won it."

Venus, a five-time Wimbledon champion, didn't face a single break point in the first set while breaking Ivanovic twice.

"Obviously it's great, no breaks of serve," Williams said. "To be honest, I thought she played really well and when she had the chance to strike the ball she was hitting the corners, so I felt good to be able to get on top of her today."

Ivanovic had her only break point at 1-0 in the second set, but Williams sent down a 122-mph first serve to save it before breaking twice more.

Williams had little expectation of what she might achieve at her first tournament since January, and her goal is to play as many matches as possible leading into Wimbledon.

"I was hoping not to be injured this week. The first smash was definitely nerve wracking," she said. "Just hoping to come off the court on two legs — that was the first goal. Then to win a match is the ultimate goal. To have the opportunity to play another match is a great start. … I just need matches."

Venus will face Daniela Hantuchova, who stopped French Open winner Li Na 7-6 (9-7), 6-3. Li held five set points in the tiebreaker and led 3-1 in the second set before losing the last five games.

"I'm still happy I play two matches in here," Li said. "Still have three days until Wimbledon, so of course now hard working and prepare."

Defending champion Ekaterina Makarova of Russia lost 7-6 (10-8), 7-6 (7-4) to Czech Petra Kvitova after holding three set points in the first-set tiebreaker and a set point at 6-5 in the second set.

Top-seeded Jo-Wilfried Tsonga lost to Radek Stepanek 6-2, 6-3. Tsonga played the final at Queen's Club on Monday and singles and doubles on Tuesday. The Frenchman admitted his busy schedule had taken its toll.

"It was difficult for me today because I played doubles last night and I didn't recover enough," he said.

The only remaining seed, No.3 Janko Tipsarevic, defeated Britain's James Ward 6-3, 4-6, 6-2 in a first-round match that had been suspended overnight at one set all. His second-round match against Russian Mikhail Kukushkin was halted by rain early in the first set.

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